This invention relates to an apparatus for collection and reduction of yard debris in thick layers and deep piles.
Homeowners, commercial-property owners, and companies who provide care for lawns have an ongoing challenge of how to remove leaves, grass clippings, and other debris from lawns, gardens and paved surfaces, particularly when the debris accumulates to a depth of over an inch. Several companies now manufacture and sell combination vacuum-chipper-shredder machines intended for this purpose. Some U.S. patents illustrating the range of these machines are as follows: U.S. Pat. Nos. 5,931,396 and 5,799,365, both assigned to MTD Products; U.S. Pat. Nos. 5,381,970 and 5,231,827, both assigned to Garden Way Incorporated; and U.S. Pat. No. 5,642,864, assigned to Simplicity Manufacturing, Inc. However, the dilemma with many prior-art units is that while they are reasonably adapted to vacuum a thin layer of debris from the ground, they do not function well when there is a thick layer of leaves or other debris. When there is a covering of several inches of leaves, the collector duct merely pushes a stack of leaves ahead of the unit instead of drawing the leaves into the machine. If the collector duct is raised to be able to take leaves from the top of the overlayer, it is no longer so effective in collecting the leaves and other debris close to the ground. Accordingly, while the available machines are somewhat effective in removing the thin layers of debris, the task of collecting thick layers of debris, particularly deep piles of leaves, remains quite problematic. Typical prior art machines, such as those shown in U.S. Pat. Nos. 5,799,365 and 5,231,827, have a vacuum pick-up opening wherein the plane of the opening is parallel to the ground, while the device shown in U.S. Pat. No. 5,642,864 has its opening disposed at an angle of about 45 degrees with respect to the ground. Such devices are poorly adapted to the tasks for which machine assistance is needed most.
Many existing machines depend primarily on flow of air to lift and entrain the leaves and other debris for transport through chipper shredder devices, and then to blow the reduced debris into accumulation units. To separate the debris from the air in which it is entrained, the machines rely on some form of filtration, with either fabric bags or screens. However, as leaf fragments and other debris collect on the filter, resistance to the flow of air increases, diminishing the air flow rate, and thereby, reducing the effectiveness of the vacuum pick-up opening.
It is an object of the present invention to provide a machine which effectively removes deep piles of leaves and other debris. In preferred embodiments, the thin layer of residual debris which might otherwise be left for later removal in another step is cleanly removed at the same time.
Another object of the invention is to provide a unit combining a front-facing vacuum-assisted opening with a rotor which serves to impel heavy leaves and debris toward a vacuum slot while creating air flow close to the surface to be cleaned in a direction which is generally parallel to that surface for picking up finer debris.
Another object of the invention is to provide a rotor-vacuum combination which both frontally engages piles of leaves and other debris and also brushes the leaves and other debris from the surface to be cleaned while entraining the debris in an air stream whence the debris may be reduced in size.
Another object of the invention is to provide a means for separating the air stream with entrained debris into a solids-depleted stream and a solids-enriched stream for collection and disposition of the debris.
It is another object of the present invention to remove deep piles of leaves and other debris.
These objects are provided by an apparatus for collection and reduction of yard debris comprising a combination of a frontally facing rotor-assisted vacuum pick up, a chipper-shredder-blower unit which (i) induces an airflow for entraining the debris collected at said pick up; (ii) reduces the debris entrained in the airflow to a more manageable volume and (iii) impels the reduced debris to a free-flow-separator device for removing the debris from the air in which it is entrained.
More particularly, this invention relates to an apparatus for collecting yard debris comprising: a frame having a shredder blower unit mounted thereupon; a collector-rotor mounted on the frame comprising impeller elements adapted to: (i) engage a surface, (ii) collect yard debris thereupon, and (iii) impel the yard debris toward the shredder blower unit; an air-solids separator mounted on the frame operatively connected to the shredder blower unit for separating the yard debris into a debris-enriched stream and a debris-depleted stream by action of body forces thereupon; and an accumulation chamber adapted to receive the debris-enriched stream from the air-solids separator; wherein the collector rotor means is configured for substantially untrammeled engagement with yard debris having a depth of at least about two (2) inches.
In another aspect this invention relates to an apparatus for collecting yard debris comprising: a frame; a shredder blower unit mounted on the frame; a collector rotor mounted on the frame comprising impeller elements adapted to: (i) engage a surface, collect yard debris thereupon, and (ii) impel said the debris toward the shredder blower unit; an air-solids separator mounted on the frame operatively connected to the shredder blower unit for separating the yard debris into a debris-enriched stream and a debris-depleted stream; and an accumulation chamber adapted to receive the debris-enriched stream from the air-solids separator; wherein the collector rotor is configured for substantially untrammeled engagement with yard debris having a depth of at least about two (2) inches.
In still another aspect this invention relates to an apparatus for collecting yard debris comprising: (A) a frame; (B) a shredder blower unit mounted on the frame; (C) a collector rotor mounted on the frame comprising impeller elements adapted to: (i) engage a surface, collect yard debris thereupon, and (ii) impel the yard debris toward the shredder blower unit; (D) an air-solids separator means mounted on the frame operatively connected to the shredder blower unit for separating the yard debris into a debris-enriched stream and a debris-depleted stream by action of body forces thereupon; and (E) an accumulation chamber adapted to receive the debris-enriched stream from the air-solids separator.
Yet another aspect of this invention relates to an apparatus for collecting and reducing yard debris comprising: (A) a frame adapted for movement in a principal direction upon a surface; (B) a first duct mounted on the frame having an entrance and an exit; (C) a collector rotor assembly comprising: a collector rotor body disposed at the entrance to the first duct having a substantially horizontal axis of rotation generally normal to the principal direction; and a plurality of impeller elements mounted upon the collector rotor body, wherein the impeller elements extend radially from the collector rotor body by at least about one quarter of an inch and are adapted to: (i) sweep over the surface, (ii) collect yard debris thereupon, and (iii) impel the yard debris toward the duct entrance, wherein the collector rotor assembly and the first duct are configured for substantially untrammeled frontal engagement with yard debris having a depth of at least about two (2) inches; (D) a second duct mounted upon the frame having an entrance and an exit; (E) a shredder blower unit, disposed between the exit to the first duct and the entrance to the second duct, adapted to: (i) provide suction at the entrance of the first duct; (ii) induce a flow of air through the first and second ducts; and (iii) reduce yard debris entrained in the flow of air as it passes through the shredder blower unit; (F) an air-solids separator disposed at the exit to the second duct for separating the reduced yard debris in the flow of air induced by the shredder blower into a debris-enriched stream and a debris-depleted stream; (G) an accumulation chamber mounted on the frame adapted to receive the debris-enriched stream from the air-solids separator; and (H) a power source mounted on the frame adapted to provide power to the shredder blower unit and the collector rotor.
In a preferred embodiment of the invention the impeller elements extend radially at least about an inch from the collector rotor body.
In another preferred embodiment the collector rotor assembly comprises a substantially gas-impervious impediment to unrestricted flow of air into the first duct and extends substantially athwart the entrance to the first duct.
A preferred collector rotor assembly comprises three impeller elements generally equispaced around the collector rotor body.
A more preferred collector rotor assembly further comprises fillets extending between adjacent impeller elements for limiting carriage of yard debris around the collector rotor assembly, wherein the fillets partially define generally concentric interrupted annular cavity spaces between adjacent impeller elements.
In a more preferred embodiment of this invention, a housing serves to limit the flow of air between the housing and the collector rotor assembly without substantially impeding air flow along the surface under the collector rotor assembly and into the entrance of the first duct; wherein this housing: (i) is disposed above the collector rotor assembly, (ii) is an arcuate portion of a generally cylindrical shell spanning an upper portion of the collector rotor assembly concentric to the axis of rotation of the collector rotor body, and (iii) engages each of the impeller element tips in flow-limiting proximity seriatim.
In another preferred embodiment, vertically extending seals are carried on the frame adjacent to the ends of the collector rotor assembly for limiting axial flow of airflow into the rotor assembly.
In another embodiment, vertically extending seals carried on the ends of the collector rotor assembly limit axial flow of airflow into the rotor assembly.
In a preferred embodiment, the housing means defines a frontal opening extending from the surface vertically to a height of at least four inches and a suction opening under the rotor extending rearwardly from the front of the apparatus at least to a line below the axis of rotation of the collector rotor body.
In another preferred embodiment, the impeller elements mounted on the collector rotor body are configured to allow intermittent rearward rushes of air under the forward side of the rotating rotor body into the entrance to the first duct, and pulsed forward rushes of air under the first duct and into the first duct entrance, thereby alternatingly collecting principally bulky yard debris from the forward side of the rotor body during the rearward rushes of air and enhancing collection of residual debris from the surface during the pulsed forward rushes of air.
A preferred embodiment of the invention further comprises an air-slot defined within the housing between the upper lip of the housing and the entrance to the first duct for allowing flow of air in a direction opposed to the direction of rotation of the collector rotor body and into the first duct and therein stripping leaves and debris from the rotating rotor assembly.
In another embodiment, the entrance to the first duct generally spans the length of the collector rotor body, and the duct converges rearwardly such that the convergence angle throughout the duct is generally less than 100 degrees.
In one embodiment, the shredder blower unit comprises a rotatable shaft having shredder elements mounted thereupon, wherein the axis of rotation of the shaft is parallel to the principal direction.
In a preferred embodiment of the invention, the air-solids separator comprises: (A) a first passage for accepting the flow of air bearing entrained reduced yard debris from the second duct; (B) a separation chamber adapted to receive the flow of air from the first passage; (C ) a second passage adapted to exhaust the debris-depleted stream from the separation chamber into the atmosphere; and (D) a baffle for: (i) generally inhibiting secondary flow from the accumulation chamber; and (ii) impeding re-entrainment of fine particulates in the debris-depleted stream as it is discharged to the atmosphere; wherein the baffle is disposed to permit passage of entrained reduced yard debris into the accumulation chamber while impeding passage of fine particulates of reduced yard debris in air exhausted from the separation chamber through the second passage.
In a more preferred embodiment, the air-solids separator separates the reduced yard debris in the airflow induced by the shredder blower into a debris-enriched stream and a debris-depleted stream by action of body forces thereupon, wherein the separator comprises: (A) a separation chamber; (B) a first declivously extending curvilinear passage for conducting the flow of air bearing the entrained reduced yard debris from the second duct into the separation chamber, wherein the separation chamber adjoins the declivously extending curvilinear passage and is adapted to receive and direct the flow of air bearing debris from the declivously extending curvilinear passage in a direction generally tangential to the perimeter of the separation chamber; (C) a generally centrally located upwardly extending second passage for exhausting the debris-depleted stream from the separation chamber into the atmosphere; (D) a baffle extending generally outwardly from a central point below the entrance to the second passage, wherein the baffle is disposed generally below the exit from the declivously extending curvilinear first passage; and (E) an opening around the baffle into the accumulation chamber; wherein the baffle is disposed to permit passage of entrained reduced yard debris in the debris-enriched stream into the accumulation chamber while impeding secondary flows of air containing finely reduced debris fragments from re-entering the separation chamber.
In an embodiment, the shredder blower unit further comprises a chipper knife adapted to chip branches.
In another embodiment, the power source further comprises a means for supplying power to wheels mounted on the frame, thereby powering forward movement of the apparatus.
In one embodiment, the air-solids separator means further comprises an enclosure having at least one filtering element, and the airflow passes through the filtering element, leaving the yard debris retained in the enclosure.
Another aspect of the invention relates to an apparatus for collecting yard debris comprising: (A) a frame adapted for movement in a principal direction upon a surface; (B) a duct mounted on the frame having an entrance and an exit; (C) a collector rotor assembly comprising: a substantially impervious collector rotor body disposed and extending substantially athwart the entrance to the duct and having a substantially horizontal axis of rotation generally normal to the first direction; and a plurality of impeller elements mounted upon the collector rotor body, extending radially from the collector rotor body by at least about one quarter of an inch, and having approximately equal radial extensions from the axis of rotation of the collector rotor assembly, wherein the impeller elements are adapted to: (i) sweep over the surface, (ii) collect yard debris thereupon, and (iii) impel the yard debris into the duct entrance; (D) a housing disposed adjacent the entrance to the duct for limiting the flow of air between the housing and the collector rotor assembly without substantially impeding air flow along the surface under the collector rotor assembly and into the entrance of the duct, wherein the housing: (i) is disposed above the collector rotor assembly; (ii) engages each of the impeller element tips in flow-limiting proximity seriatim; and (iii) is configured to permit substantially untrammeled frontal engagement of the collector rotor assembly with yard debris having a depth of at least about two (2) inches; (E) an air-movement device connected to the exit of the duct and adapted to: (i) provide suction at the entrance of the duct, and (ii) induce a flow of air through the duct; and (F) a power source mounted upon the frame adapted to provide power to the air-movement device and the collector rotor.
In a preferred embodiment of the invention, the tips of the impellers further comprise pliable blades that are yieldable to hard objects encountered on the surface, but are sufficiently stiff to sweep debris from the undulating surface.
In a more preferred embodiment, the tips of the impellers comprise radially extending raker teeth adapted to engage and impel debris objects on the surface toward the duct entrance.
In a further embodiment, the housing comprises an arcuate portion of a generally cylindrical shell spanning an upper portion of the collector rotor assembly generally concentric to the axis of rotation of the collector rotor body, and which is disposed in flow-limiting proximity to at least one tip of one of the impeller elements during at least about one fourth of the time of each revolution of the collector rotor assembly.
In an embodiment, the duct is disposed such that a space at least xc2xd inch thick is preserved between the bottom of the duct and the surface, permitting forward air flow toward the duct entrance.
In a preferred embodiment, the cross-sectional area of the channel through the duct measured normal to the center flow line of the airflow through the duct remains generally constant along the center flow line.
In a further embodiment, the collector rotor assembly and the entrance of the duct are disposed along the advancing front of a lawnmower having a cutting path of a defined width.
In a preferred embodiment, the collector rotor assembly impels the yard debris into the mowing chamber within the mowing enclosure of the lawnmower.
In a more preferred embodiment, the air-movement means achieves an airflow volume of at least about twenty cubic feet per minute per inch of collector rotor assembly length.
In another preferred embodiment the present invention relates to an apparatus for separating entrained lawn debris from a transporting air stream by action of body forces thereupon comprising: (A) an apparatus for delivering a stream of air bearing entrained lawn debris; (B) a first passage having an entrance and exit, having the entrance adapted to receive the stream of air bearing entrained lawn debris, and the passage adapted for conducting the flow of air bearing entrained lawn debris from the entrance to the exit; (C) a separation chamber having a generally cylindrical outer wall section, with the separation chamber: (i) connected to the exit from the first passage; and (ii) adapted to: (a) receive and direct the stream of air bearing entrained lawn debris from the first passage in a direction primarily tangential to the generally cylindrical outer wall section of the separation chamber, and (b) separate the stream of air bearing entrained lawn debris into an outerly located debris-enriched stream and an innerly located debris-depleted stream; (D) an upper bulkhead to the separation chamber having defined therein, a generally centrally located second passage having an entrance and an exit, with the generally centrally located second passage adapted for: (i) receiving the innerly located debris-depleted stream from the separation chamber through the entrance, and (ii) conducting the innerly located debris-depleted stream to the exit and discharging it into the atmosphere; (E) the bulkhead of said separation chamber further: (i) extending generally horizontally from the second passage generally outwardly to the substantially cylindrical outer wall, and (ii) being disposed at generally the same height as the entrance to the second passage; (F) a baffle extending generally outwardly from a central point below the entrance to the second passage, wherein the baffle is disposed generally below the exit of the first passage, and the outer periphery of the baffle is spaced inwardly from the generally cylindrical outer wall section; and (G) an opening around the baffle into the interior of an accumulation chamber below the baffle; wherein the baffle is disposed to permit passage of entrained yard debris into the accumulation chamber while impeding passage of fine particulates of reduced yard debris from the accumulation chamber into the debris-depleted stream discharged from the separation chamber through the second passage.
Preferably, the plane of the said baffle periphery is disposed below the lowermost portion of the upper bulkhead by a distance of less than about 0.6 times the inside diameter of the separation chamber.
In another preferred embodiment, the baffle periphery is disposed below the lowermost portion of the entrance to the second passage by a distance of less than about 0.6 times the inside diameter of the separation chamber.
In one embodiment the upper bulkhead of the separation chamber further comprises a substantially planar surface generally normal to the axis of the substantially cylindrical outer wall and has an opening comprising the entrance of the second passage.
In another embodiment, the upper bulkhead of the separation chamber further comprises a generally semi-toroidal surface and has an opening comprising the entrance of the second passage.
Preferably, the upper bulkhead has as its substantially only interruptions, openings comprising the exit of the first passage and the entrance of the second passage.
In a more preferred embodiment, the first passage extends declivously from its entrance toward its exit and directs the stream of air bearing entrained lawn debris into the separation chamber.
Preferably, (A) the first passage is curvilinear in a plane generally perpendicular to the axis of the generally cylindrical outer wall section, (B) the outer wall of the curvilinear passage is disposed approximately coincident with the generally cylindrical outer wall section of the separation chamber, and (C) the generally cylindrical outer wall section of the separation chamber is disposed at least about three inches outward from the perimeter of the entrance to the second passage.
In a preferred embodiment, the generally cylindrical outer wall section of the separation chamber is disposed at least about five inches outwardly from the perimeter of the entrance to the second passage.
In a preferred embodiment, the baffle further comprises an upright cone having its apex pointing toward the entrance of the second passage.
Preferably, the cone periphery and the outer wall section of the separation chamber are generally circular.
In a preferred embodiment, the opening around the periphery further comprises an annular opening between the periphery of the baffle and the outer wall section of the separation chamber.
Preferably, the vertical distance from the apex of the cone to the plane of the entrance of the second passage is less than about 0.6 times the diameter of the entrance to the second passage.
In one embodiment, the accumulation chamber is approximately cylindrical and has a slidable opening in a plane at an angle of about 75 degrees to about 90 degrees to the axis of the cylinder.
In a preferred embodiment, the stream of air bearing entrained lawn debris swirls around the separation chamber with a tangential perimeter velocity of at least about 2000 feet per minute, causing the entrained reduced lawn debris to move toward the generally cylindrical outer wall of the separation chamber by action of body forces thereupon.
Preferably, the radial distance from the baffle periphery to the outer wall of the separation chamber is less than about one fourth of the inside diameter of the separation chamber, measured in approximately the same plane as the plane of the baffle periphery.
In another embodiment, the accumulation chamber further comprises a flexible bag-like container, such as a paper bag or a plastic bag.
In still another embodiment, the device for delivering a stream of air bearing entrained lawn debris further comprises a lawnmower having a discharge duct connected to the entrance of the first passage.
In another aspect, this invention relates to a free-flow apparatus for separating entrained lawn debris from a transporting air stream by action of body forces thereupon comprising: (A) an apparatus for delivering a stream of air bearing entrained lawn debris; (B) a first passage having an entrance and exit, with the entrance adapted to receive the stream of air bearing entrained lawn debris, and the passage adapted for conducting the stream of air bearing entrained lawn debris from the entrance to the exit; (C) a separation chamber having a generally frusto-conical outer wall section, with the separation chamber: (a) connected to the exit from the first passage; and (b) adapted to: (i) receive and direct the stream of air bearing entrained lawn debris from the first passage in a direction primarily tangential to the frusto-conical outer wall section of the separation chamber, and (ii) separate the stream of air bearing entrained lawn debris into an outerly located debris-enriched stream and an innerly located debris-depleted stream; (D) a generally centrally located second passage having an entrance and an exit, and being adapted for (i) receiving the innerly located debris-depleted stream from the separation chamber through the entrance, and (ii) conducting the innerly located debris-depleted stream to the exit and discharging it into the atmosphere; (E) an upper bulkhead to the separation chamber having defined therein a generally centrally located second passage having an entrance and an exit, with the upper bulkhead extending from the second passage generally outwardly to the generally frusto-conical outer wall section; (F) a baffle extending generally outwardly from a central point below the entrance to the second passage, and disposed generally below the exit of the first passage, wherein the outer periphery of the baffle is disposed inwardly from the generally frusto-conical outer wall section, and below the uppermost portion of the first passage by a distance of less than 1.2 times the inside diameter of the separation chamber proximate the baffle; and (G) an opening around the baffle into the interior of an accumulation chamber below the baffle; wherein the baffle is disposed to permit passage of entrained yard debris into the accumulation chamber while impeding passage of fine particulates of reduced yard debris from the accumulation chamber into the air discharged from the separation chamber through the second passage.
In a preferred embodiment, (A) the first passage is curvilinear in a plane generally perpendicular to the axis of the generally cylindrical outer wall, (B) the outer wall of the curvilinear passage is disposed generally coincident with the generally frusto-conical outer wall section of said separation chamber, (C) the bulkhead is disposed at generally the same height as the entrance to the second passage, and (D) the generally frusto-conical outer wall section of the separation chamber is disposed at least about three inches radially outward from the perimeter of the entrance to the second passage.
Preferably, the first passage comprises substantially the only passage for conducting air flow into the separation chamber, and the second passage comprises substantially the only passage for conducting the innerly located debris-depleted stream out of the separation chamber.
In a preferred embodiment, the device for delivering a stream of air bearing entrained reduced lawn debris further comprises a shredder blower.
In another aspect, this invention relates to a free-flow apparatus for separating entrained lawn debris from a transporting air stream by action of body forces thereupon comprising: (A) an apparatus for delivering a stream of air bearing entrained lawn debris; (B) a primary-separation duct having an entrance and exit, wherein the entrance is adapted to receive the stream of air bearing entrained lawn debris, the duct is adapted for conducting the stream of air bearing entrained lawn debris from the entrance to the exit; and the primary-separation duct has a generally curvilinear outer surface spanning an arc of at least about
arc cosine (RI/RO)
circumferentially along its length, having the primary-separation duct adapted to direct the stream of air bearing entrained lawn debris to flow generally circumferentially along its length and initiate separation of the stream of air bearing entrained lawn debris into an outerly located debris-enriched stream and an innerly located debris-depleted stream, wherein
RI=radius of curvature for the generally curvilinear inner surface of the primary-separation duct, and
RO=radius of curvature for the generally curvilinear outer surface;
(C) a secondary-separation chamber connected to the exit from the primary-separation duct and having a generally annular outer wall defining a primary axis generally co-incident with the center of curvature of the generally annular outer wall, the functions of the secondary-separation chamber further comprising (i) receiving and directing the streams of air bearing entrained lawn debris from the primary-separation duct in a direction generally tangential to the generally annular outer wall of the secondary-separation chamber, (ii) directing the outerly located debris-enhanced stream from the primary-separation duct to flow adjacent to the outer wall of the secondary-separation chamber, (iii) directing the innerly located debris-depleted stream from the primary-separation duct to flow radially inward of the debris-enriched stream, and (iv) further separating the streams of air bearing entrained lawn debris into an upwardly and inwardly directed debris-depleted stream and a downwardly and outwardly directed debris-enriched stream; (D) a generally centrally located passage having an entrance and an exit, and being adapted for: (i) receiving the upwardly and inwardly directed debris-depleted stream from the secondary-separation chamber through the entrance, and (ii) conducting this stream to the exit and discharging it into the atmosphere; (E) a baffle extending generally outwardly from a central point below the entrance to the passage, having the outer periphery of the baffle spaced inwardly from the generally annular outer wall; and (F) an opening around the baffle into the interior of an accumulation chamber below the baffle; wherein the baffle is disposed to permit passage of entrained yard debris in the downwardly and outwardly directed debris-enriched stream into the accumulation chamber while impeding passage of fine particulates of reduced yard debris from the accumulation chamber into air discharged from the separation chamber through the passage.
Preferably, the baffle periphery is disposed below the uppermost portion of the primary-separation duct by a distance of less than 1.2 times the inside diameter of the secondary-separation chamber having a generally annular outer wall, with this inside diameter being measured in the plane of the baffle periphery.
More preferably, the baffle periphery plane is disposed below the uppermost portion of the entrance to the passage by a distance of less than about 0.6 times the inside diameter of the secondary-separation chamber having a generally annular outer wall, with this inside diameter being measured in the plane of the baffle periphery.
In one embodiment, the axis of curvature of the primary-separation duct is disposed generally coincident with the primary axis.
Still another aspect of this invention relates to a free-flow apparatus for separating entrained lawn debris from a transporting air stream by action of body forces thereupon comprising: (A) an apparatus for delivering a stream of air bearing entrained lawn debris; (B) a separation chamber having an upper bulkhead and an outer wall; (C) a first passage having an entrance and exit, having the entrance adapted to receive the stream of air bearing entrained lawn debris, and being adapted for conducting the stream of air bearing entrained lawn debris from the entrance to the separation chamber and directing the stream of air bearing entrained lawn debris into the separation chamber in a direction primarily tangential to the outer wall of the separation chamber; wherein the separation chamber is adapted to separate the stream of air bearing entrained lawn debris into an outerly located debris-enriched stream and an innerly located debris-depleted stream; (D) a generally centrally located second passage having an entrance and an exit, wherein the generally centrally located second passage is adapted for: (i) receiving the innerly located debris-depleted stream from the separation chamber through the entrance, and (ii) conducting the innerly located debris-depleted stream to the exit and discharging it into the atmosphere; (E) a baffle extending generally outwardly from a central point below the entrance to the second passage; having the outer periphery of the baffle spaced inwardly from the outer wall; and (F) an opening around the baffle into the interior of an accumulation chamber below the baffle, having the baffle disposed to permit passage of the innerly located debris-depleted stream into the second passage while impeding passage of fine particulates of reduced yard debris from the accumulation chamber into the air discharged from the separation chamber through the second passage; wherein the overall height of the apparatus from the uppermost portion of the apparatus to the plane of the outer periphery of the baffle is less than about 1.2 times the inside diameter of the separation chamber proximate the baffle periphery.
Preferably, the connection of the exit of the first passage into the separation chamber is disposed below the upper bulkhead.
In a preferred embodiment, the first passage is curvilinear in a plane generally perpendicular to the axis of the outer wall and has its concave surface generally concentric about the axis.
Yet another aspect of this invention relates to a free-flow apparatus for separating entrained lawn debris from a transporting air stream by action of body forces thereupon, comprising: (A) an apparatus for delivering a stream of air bearing entrained lawn debris having a flow rate of at least about 300 cubic feet per minute; (B) a primary-separation duct having an entrance and exit, with the entrance adapted to receive the stream of air bearing entrained lawn debris, and the duct adapted for conducting the stream of air bearing entrained lawn debris from the entrance to the exit; wherein the primary-separation duct (i) has a generally curvilinear outer surface spanning an arc of at least about
arc cosine RI/RO
circumferentially along its length and has a radius of curvature of its generally curvilinear outer surface less than about 36xe2x80x3, (ii) measures at least about 4xe2x80x3 perpendicular to its plane of curvature and at least about 2xe2x80x3 in the radial direction, and (iii) is adapted to direct the stream of air bearing entrained lawn debris to flow generally circumferentially along its length and initiate separation of the stream of air bearing entrained lawn debris into an outerly located debris-enriched stream and an innerly located debris-depleted stream, wherein
RI=radius of curvature of the generally curvilinear inner surface of the primary-separation duct, and
RO=radius of curvature of the generally curvilinear outer surface;
(C) a secondary-separation chamber less than about 36xe2x80x3 in diameter and connected to the exit from the primary-separation duct and having a generally annular outer wall defining a primary axis generally co-incident with the center of curvature of the generally annular outer wall, the secondary-separation chamber further comprising a shape for (i) receiving and directing the streams of air bearing entrained lawn debris from the primary-separation duct in a direction generally tangential to the generally annular outer wall of the secondary-separation chamber, (ii) directing the outerly located debris-enhanced stream from the primary-separation duct to flow along the outer wall of the secondary-separation chamber; (iii) directing the innerly located debris-depleted stream from the primary-separation duct to flow radially inward of the debris-enriched stream; and (iv) further separating the streams of air bearing entrained lawn debris into an upwardly and inwardly directed debris-depleted stream and a downwardly and outwardly directed debris-enriched stream; (D) a generally centrally located passage at least 4xe2x80x3 in diameter and having an entrance and an exit, and having the perimeter of the entrance located at least 2xe2x80x3 radially inward from the generally annular outer wall of the secondary-separation chamber, wherein the generally centrally located passage is adapted for: (i) receiving the upwardly and inwardly directed debris-depleted stream from the secondary-separation chamber through the entrance, and (ii) conducting the upwardly and inwardly directed debris-depleted stream to the exit and discharging it into the atmosphere; (E) a baffle extending generally outwardly from a central point below the entrance to the passage, having the outer periphery of the baffle spaced at least 1xe2x80x3 inwardly from the generally annular outer wall, and having the outer periphery disposed less than 15xe2x80x3 below the entrance to the passage; and (F) an opening around the baffle into the interior of an accumulation chamber below the baffle; wherein the baffle is disposed to permit passage of entrained yard debris in the downwardly and outwardly directed debris-enriched stream into the accumulation chamber while impeding passage of fine particulates of reduced yard debris from the accumulation chamber into air discharged from the separation chamber through the passage.